scholarly journals Numerical Simulation on Open Wellbore Shrinkage and Casing Equivalent Stress in Bedded Salt Rock Stratum

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jianjun Liu ◽  
Linzhi Zhang ◽  
Jinzhou Zhao
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Finite Difference ◽  
Elasticity Modulus ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Salt Rock ◽  
Rock Stratum ◽  
Casing Strength

Most salt rock has interbed of mudstone in China. Owing to the enormous difference of mechanical properties between the mudstone interbed and salt rock, the stress-strain and creep behaviors of salt rock are significantly influenced by neighboring mudstone interbed. In order to identify the rules of wellbore shrinkage and casings equivalent stress in bedded salt rock stratum, three-dimensional finite difference models were established. The effects of thickness and elasticity modulus of mudstone interbed on the open wellbore shrinkage and equivalent stress of casing after cementing operation were studied, respectively. The results indicate that the shrinkage of open wellbore and equivalent stress of casings decreases with the increase of mudstone interbed thickness. The increasing of elasticity modulus will reduce the shrinkage of open wellbore and casing equivalent stress. Research results can provide the scientific basis for the design of mud density and casing strength.

scholarly journals Application of Multiphysics Coupling FEM on Open Wellbore Shrinkage and Casing Remaining Strength in an Incomplete Borehole in Deep Salt Formation

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Hua Tong ◽  
Daqiang Guo ◽  
Xiaohua Zhu
Keyword(s):  
Three Dimensional ◽  
Effect Of Temperature ◽  
Salt Rock ◽  
Salt Formation ◽  
Defect Level ◽  
Rock Creep ◽  
Multiphysics Coupling ◽  
Casing Strength ◽  
New Perspective ◽  
Harsh Condition

Drilling and completing wells in deep salt stratum are technically challenging and costing, as when serving in an incomplete borehole in deep salt formation, well casing runs a high risk of collapse. To quantitatively calculate casing remaining strength under this harsh condition, a three-dimensional mechanical model is developed; then a computational model coupled with interbed salt rock-defective cement-casing and HPHT (high pressure and high temperature) is established and analyzed using multiphysics coupling FEM (finite element method); furthermore, open wellbore shrinkage and casing remaining strength under varying differential conditions in deep salt formation are discussed. The result demonstrates that the most serious shrinkage occurs at the middle of salt rock, and the combination action of salt rock creep, cement defect, and HPHT substantially lessens casing remaining strength; meanwhile, cement defect level should be taken into consideration when designing casing strength in deep salt formation, and apart from the consideration of temperature on casing the effect of temperature on cement properties also cannot be ignored. This study not only provides a theoretical basis for revealing the failure mechanism of well casing in deep complicated salt formation, but also acts as a new perspective of novel engineering applications of the multiphysics coupling FEM.

Numerical Simulation of Heat Transfer in a Closed Two-Phase Thermosiphon

2017 ◽  
Vol 743 ◽  
pp. 449-453
Author(s):  
Vladimir Arkhipov ◽  
Alexander Nee ◽  
Lily Valieva
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Phase Transitions ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Mathematical Modelling ◽  
Three Dimensional ◽  
Two Phase ◽  
One Dimensional ◽  
The Finite Difference Method

This paper presents the results of mathematical modelling of three–dimensional heat transfer in a closed two-phase thermosyphon taking into account phase transitions. Three-dimensional conduction equation was solved by means of the finite difference method (FDM). Locally one-dimensional scheme of Samarskiy was used to approximate the differential equations. The effect of the thermosyphon height and temperature of its bottom lid on the temperature difference in the vapor section was shown.

Vibration transmission path identification in a hydropower house based on a time-delayed transfer entropy method

2020 ◽  
Vol 26 (15-16) ◽  
pp. 1214-1227
Author(s):  
Liaojun Zhang ◽  
Shuo Wang ◽  
Guojiang Yin ◽  
Chaonian Guan
Keyword(s):  
Information Transmission ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Entropy Method ◽  
Transfer Entropy ◽  
Vertical Acceleration ◽  
Vibration Transmission ◽  
Transmission Path ◽  
Hydropower House

This article aims to explore the vibration transmission path in the hydropower house using the time-delayed transfer entropy method. A three-dimensional fluid-concrete structure-hydraulic machinery coupling simulation model of the Xiangjiaba hydropower house was established, and the vibration acceleration and equivalent stress of the structure were calculated in the time domain based on the two-way iterative fluid-structure interaction method. The characteristic indexes of information transmission were quantitatively presented, including the rate of information transmission, transmission path contribution, to describe the vibration energy transmission paths and transmission characteristics of different vibration variables as well as different directions of the same variable in the hydropower house. The study indicates that the vertical acceleration can identify more abundant vibration transmission paths, and the lower bracket contributes most to the vibration transmission of the powerhouse. The research outcome can provide a scientific basis for structural optimization, vibration attenuation, and isolation design of the hydropower house.

Three-dimensional numerical simulation of air flow and fiber dynamic in carding region in carding machine

2019 ◽  
Vol 89 (19-20) ◽  
pp. 3916-3926
Author(s):  
Shanshan He ◽  
Longdi Cheng ◽  
Wenliang Xue ◽  
Zhong Lu ◽  
Liguo Chen
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Finite Element ◽  
Flow Field ◽  
Axial Velocity ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Element Model ◽  
Mechanical Analysis ◽  
Field Simulation

Regular cylinder metallic card clothing has a limited carding efficiency. As a result of the limited dimensions, any measurement between the cylinder and flat area is difficult to make. In this study, an approach is first proposed to simulate the flow field and a fiber finite-element model on the moving surface of the teeth and produce a new design of misaligned-teeth card clothing, with the aim of improving the carding efficiency. A comparison is made between regular and misaligned-teeth card clothing types with respect to flow field simulation and fiber mechanical properties. The results show that the force resulting from the tangential velocity between the cylinder and flat is as great as 1.86 × 10−3 N, sufficient to pull fiber out of tufts, and that the tangential velocity (from 3880 to 2500 mm/s) plays a major role in this area, as opposed to the axial velocity (from 0 to 190 mm/s). Through this comparison, the misalignment design can result in a different tangential velocity distribution from that of traditional card clothing, which helps fibers between two lines of teeth move into neighboring lines of teeth, thereby increasing the likelihood that fibers will be carded. For fiber mechanical analysis, different air forces are loaded on fibers. This comparison shows that for fibers in the channel, the misalignment can help fibers move toward the teeth. Therefore, this misaligned-teeth card clothing is thought to prove more effective in practice.

Nuclide u Transport in Radioactive Waste Disposal Field with Weak Permeable Media

2013 ◽  
Vol 353-356 ◽  
pp. 1175-1178
Author(s):  
Ying Er Deng ◽  
Wei Zhang ◽  
Ying Zi Chen
Keyword(s):  
Numerical Simulation ◽  
Radioactive Waste ◽  
Conceptual Model ◽  
Waste Disposal ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Radioactive Waste Disposal ◽  
Prevention Measures ◽  
Permeable Media ◽  
Good Agreement

This paper took nuclide U as a research object and focused on nuclide U transport. Three-dimensional conceptual model was established for nuclide U transport in certain a radioactive waste disposal field with weak permeable media. Nuclide U transport in the field was studied by means of three-dimensional numerical simulation. Results show that there is good agreement between numerical simulated and observed groundwater level and that the conceptual model and the numerical simulation are reasonable. Nuclide U transport in the field will form a pollution zone after about 10 years in the mainstream direction and pollute groundwater of the southern area. Prevention measures should be adopted for nuclide U transport in the field. The results can provide evaluation of engineering safety of nuclide U transport in the field with scientific basis.

Numerical Simulation of Groundwater Flow in Strata with Argillation Weak Permeable Media in Long Deep Buried Tunnel Site

2014 ◽  
Vol 670-671 ◽  
pp. 674-677
Author(s):  
Ying Er Deng ◽  
Xin Peng ◽  
Huan Huan Jiang
Keyword(s):  
Numerical Simulation ◽  
Groundwater Flow ◽  
Conceptual Model ◽  
Water Pressure ◽  
Three Dimensional ◽  
High Water ◽  
Scientific Basis ◽  
Tunnel Construction ◽  
Prevention Measures ◽  
Permeable Media

This paper focused on groundwater flow in certain a tunnel site under conditions of high ground stress and high water pressure (referred to as “two high conditions”). Three-dimensional conceptual model was established for groundwater flow in porous strata with argillation weak permeable media in a long deep buried tunnel site. Groundwater flow field was studied by means of three-dimensional numerical simulation. Results show that there is good agreement between numerical simulated and observed groundwater table and that the conceptual model and the numerical simulation are reliable. Prevention measures should be adopted for a long deep buried tunnel construction. The results can provide evaluation of engineering safety of a long deep buried tunnel construction with scientific basis.

Application 3D Numerical Simulation on Foundation Pit Dewatering Design of Nanchang International Financial Center

2010 ◽  
Vol 108-111 ◽  
pp. 1482-1485 ◽  
Author(s):  
Gong Xin Chen ◽  
Wang Lei
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Simulation Software ◽  
Visual Modflow ◽  
Foundation Pit ◽  
Strong Basis ◽  
Design Elements ◽  
Pumping Wells ◽  
Geological Conditions

Based on the detailed analysis of site engineering geological and hydro-geological conditions for the proposed project Nanchang International Finance Center high-rise building, the dewatering design of this fundamental pit is proposed， in accordance with the surrounding environment as well as those pit design elements and so on. The three-dimensional numerical simulation model of groundwater for dewatering is also established. Using the three-dimensional groundwater numerical simulation software, Visual-modflow, the site is meshed into grid and the dewatering model is built under different well numbers and space. Al last, an optimal program (10 pumping wells for each pit and well equaling space) for this pit has been determined. It is also to simulate the water level vs. time during the dewatering. This does not only provide a strong basis for the optimum design of the foundation pit dewatering, but also provide a scientific basis for decision making to the underground construction.

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